1. Field of the Invention
The invention is directed to an architecture for a communication network and in particular to a network architecture with traffic balancing.
2. Background Art
Network users and providers are looking for reliable networks at acceptable bandwidth (BW) cost. Reliability is the ability of the network to carry the information from source to destination with errors below a certain threshold.
Protection is a traffic preserving strategy for managing the usage of the working and the dedicated protection (redundant) bandwidth in the network. Automatic protection acts at the physical layer (see OSI layers) quickly enough to ensure that the client""s connections remain unaffected by failures. SONET/SDH (synchronous optical network/synchronous digital hierarchy) is provided with very effective and fast protection mechanisms, which make this technology a strong contender for the networks of the future.
Typically, protection switching times are less than 50 ms for SONET. On the other hand, protection implies reserving bandwidth, and therefore transport networks are often 100% overbuilt.
SONET/SDH protection protocols are designed for various network configurations, such as linear networks (1+1; 1:1 and 1:N protection schemes) and ring networks (unidirectional path switched rings UPSR and bidirectional line switched rings BLSR). As well known, the two digits used to define the type of protection, refer to the number of xe2x80x9cprotectionxe2x80x9d (spare) fibers and the xe2x80x9cworkingxe2x80x9d fibers for a certain span. 1+1, UPSR and 1:1 schemes require 100% redundancy. 1:N, 2F (two-fiber)-BLSR and 4F-BLSR schemes require less than 100% network overbuild, as extra traffic (traffic of lower priority) may be carried between nodes on the protection bandwidth/fibers during normal operation conditions. The extra traffic is however lost when a protection switch occurs.
There is a need to transport traffic at high speed with a better use of the available bandwidth than afforded by the current SONET rings.
It is an object of the present invention to provide a network architecture and bandwidth (BW) balancing strategy that will allow use of more that 50% of the network capacity to transmit working traffic.
According to one aspect of the invention, there is provided a balanced network for transporting a traffic signal with a working-to-protection bandwidth ratio higher than 0.5, comprising a ring network for connecting a first node and a second node, said nodes defining a first and a second ring arm, one or more mesh arms connecting said first node and said second node, wherein each arm includes one or more ADM nodes, and each arm has a protection bandwidth of 1/NBW and a working bandwidth of (Nxe2x88x921)/N BW, where BW is the capacity available on any line of said network, and N is the number of arms connecting said first and second nodes.
According to another aspect of the invention, there is provided a balanced network for transporting a traffic signal with a working-to-protection bandwidth ratio higher than 0.5, comprising a ring network for connecting a first node and a second node, said nodes defining a first and a second ring arm, one or more mesh arms connecting said first node and said second node, wherein each arm includes one or more ADM nodes, and each arm has a working bandwidth of (Nxe2x88x92M)/N BW, where BW is the capacity available on any line of said network, N is the number of arms connecting said first and second nodes, and M is the number of full line faults in said network.
In yet another aspect of the invention, there is provided A method for creating a balanced transport network with a working/protection bandwidth ratio higher than 0.5, comprising providing N arms between a first and a second node of balanced network, each arm comprising one or more ADM nodes, allocating to each said arm a working bandwidth of (Nxe2x88x921)/N BW and a protection bandwidth of 1/N BW, where BW is the capacity available on any line of said network.
Advantageously, by allowing protection of more than 50% of the working BW, a network provider would earn more revenue per unit of BW. In addition, the solution proposed herein is simple and inexpensive to implement.